Why run electrical current through your brain (which seems like a bad idea on general principle)? Audio waves are demonstrably effective - not just for stimulat

Why run electrical current through your brain (which seems like a bad idea on general principle)? Audio waves are demonstrably effective - not just for stimulation / focus, but adjustable for other cogntitive states, like relaxation and sleep. See [Brain.FM](https://brain.fm https://brain.fm).